Stereo imaging uses planar imagers to acquire three-dimensional information about a scene. To obtain the third dimension of depth, two planar imagers are offset by a distance to determine the relative position of objects in the scene. Two types of stereo cameras using conventional cameras with photochemical film as the imager are available. In one, a special offset optics system is used to create two images on a single frame of film by opening a single shutter. In the other, two independent offset cameras with coordinated shutters are used to simultaneously expose two frames of film. Conventional cameras present certain problems as stereo cameras, however. They are complicated, expensive mechanical devices and photochemical film requires the images to be developed and converted to digital data.
The development of charge-coupled device (CCD) image sensors has led to their use in stereo cameras. A CCD image sensor comprises a two-dimensional array of photodiodes which convert received light into a charge. For stereo imaging, two CCD image sensors offset by a distance collect two images using global electronic shutters to synchronize the images. The electronic image data is then read out sequentially. CCD image sensors are expensive in themselves and less than ideal for this application. CCD image sensors require substantial off-chip support circuitry, such as power supplies, device drivers, timing generation, and analog to digital conversion. In addition, CCD image sensors use large amounts of power, requiring large battery capacity in battery-powered devices. This makes CCD-based stereo cameras complicated and expensive.
It would be desirable to have a stereo imaging system and method of using the same that would overcome the above disadvantages.